Due to its excellent mechanical strength, heat resistance, electrical property, dimensional stability, flame retardance, transparency and the like, polycarbonate is extensively used in electric, electronic and office automation equipments, optical media, automotive parts, building components and the like.
Such polycarbonate is usually produced by an interface method in which bisphenol A (aromatic dihydroxy compound) and phosgene are directly reacted with each other, a melting method in which bisphenol A and diphenyl carbonate (diester carbonate) are subjected to transesterification reaction (polycondensation reaction) in a molten state, or the like.
However, a molded product obtained from a polycarbonate-based resin that is produced using bisphenol A as an aromatic dihydroxy compound comes short in terms of surface hardness, for example, for the application to automotive headlamps, spectacle lens and outdoor use such as sheets.
Therefore, a hard coat layer is often provided on the surface of the polycarbonate-based resin to enhance the surface hardness.
Providing a hard coat layer or the like on the surface, however, increases the number of steps of the production process, which decreases the production efficiency. Furthermore, in a case where a molded product has a complicated shape, it is difficult to provide a hard coat layer.
Accordingly, a considerable number of researches on enhancing the surface hardness while maintaining the transparency by blending a specific resin into a polycarbonate-based resin have been done. As the resin to be blended into a polycarbonate-based resin, a number of cases propose to use an acrylic resin that is transparent like the polycarbonate-based resin. For example, Patent Documents 1 and 2 disclose resin compositions comprising a polycarbonate-based resin and an acrylic resin having a molecular weight in a specific range.
In addition, some cases propose to blend an acrylic copolymer. For example, Patent Documents 3 to 7 disclose resin compositions comprising a polycarbonate-based resin and a (meth)acrylic copolymer.